Tamper-proof axial tumbler-type lock



Aug. 23, 1966 w. J. KERR TAMPER-PROOF AXIAL TUMBLER-TYPE LOCK 2 Sheets-Sheet 1 Filed Feb. 15, 1965 //Vl E/V7'OR W/LL IAM J. KERR Aug. 23, 1966 w. J. KERR TAMPER-PROOF AXIAL TUMBLER-TYPE LOCK 2 Sheets-Sheet 2 Filed Febv 1.5, 1.965

//VVENTOR W/LL/AM J. KERR HTTORNE Y United States Patent 3,267,766 TAMPER-PROOF AXIAL TUMBLER-TYPE LOCK William 3. Kerr, Glenview, Ill., assignor to Chicago Lock Company, Chicago, 1th, a corporation of Illinois Filed Feb. 15, 1965, Ser. No. 432,618 9 Claims. Cl. 70-463) The present invention relates to improvements in locks and has particular reference to axial tumbler-type locks of the type wherein the various pin-variety tumblers that are associated therewith are arranged in an annular series around, and extend parallel to, the central longitudinal axis of the lock cylinder. In a lock of this general type, the tumblers slide in bores and pass from the stationary part of the lock into the rotatable part. Furthermore, the tumblers are transversely divided or split aifd are adapted to be longitudinally or axially displaced by the proper key for the lock against the resistance of helical compression springs in such a manner that their splits or joints coincide with the joint between the movable and stationary parts of the lock. For this purpose, the key which controls the lock is provided with an annular series of pusher elements which correspond in number to, and are associated respectively with, the tumblers and define rearwardly facing shoulders. These shoulders are designed for engagement with the forward exposed ends of the tumblers and are disposed at dilferent axially displaced positions which are commensurate with the distance to which the associated or respective tumblers must be forced back into the tumbler-receiving bores of the lock so that all of the tumbler splits or joints will coincide with the joint between the stationary and rotatable parts of the lock to thus permit the rotatable part to be turned by the key.

Present-day locks of the axial tumbler type as briefly outlined above are possessed of one limitation which is the purpose of the present invention to obviate, namely, that such locks are not tamper-proof and are relatively easy to pick due to the accessibility of the tumblers at the forward ends of the locks. Ordinarily, the key that is associated with an axial tumbler-type lock is provided with a tubular cylindrical rear end region which is insertable endwise into the lock through a narrow annulus which faces forwardly and directly behind which the forward ends of the tumblers are visible and exposed. This annulus exists by reason of the provision of a center post which guides the key and renders the same coaxial with the lock cylinder, and in addition, the surrounding rim of a protective cap or head on the lock cylinder, such cap being commonly referred to as a washer. Directly in line with the aforementioned annulus are the forward ends of the tumblers and there is little to prevent a contemplative tamperer from manipulating these tumblers by the use of axial thrust pins which may be caused to duplicate the action of a key. In fact, the design of conventional axial tumbler-type locks invites tampering and it would not require much ingenuity for an unauthorized person to devise a tamper jig having slidable shoulders which would readily duplicate the action of a key.

The present invention is designed to overcome the above-noted fallibility of conventional axial tumbler-type locks and toward this end, the invention contemplates the provision of an axial tumbler-type lock wherein the forward ends of the tumblers are both concealed from view and inaccessible for manipulation with an ordinary or simple lock-picking tool. In carrying out this object, the invention contemplates the provision of a lock which Patented August 23, 1966 does not deviate appreciably in construction and design from conventional axial tumbler-type locks, the key-aligning center post, protective washer and key-receiving annulus being retained with the parts cooperating with one another in the usual manner for entry of the key into the lock. However, instead of maintaining the tumblers in axial register with the key-receiving annulus as heretofore, the tumblers are displaced radially outwardly from such annulus so that they lie behind, and are concealed by, the front wall of the protective washer where they are not readily accessible for manipulation by a conventional lock-picking tool. To render the tumblers accessible to a proper key, the front wall of the protective cap or washer is radially slotted, the slots communicating with the key-receiving annulus. The key, in turn, is formed with radial shoulder-carrying fins which fit the radial slots so that the key may enter the lock endwise in the usual manner of key entry. The tumblers, however, are not in axial register with the slots, but, instead, they are circumferentially displaced therefrom so that after the key has been inserted into the lock, it is necessary to turn the key throughout a preliminary small angle to bring the fins into axial register with the tumblers, after which the key may be pushed rearwardly to depress the tumblers in the usual manner of tumbler-depression for lock unlocking purposes. The forward edges of the fins are, of course, disposed at different axial or longitudinal distances along the key, the various distances .being commensurate with the required axial tumbler displacements. Cooperating guide means immediately behind the front wall of the protective cap or washer cooperates with the key to arrest forward movement of the key until it has been turned throughout the predetermined small angle and the fins thus brought into axial register with the tumblers. From the above brief description of the tamper-proof characteristics of the present lock, it will be appreciated that to design a set of lock-picking tools for such a lock would tax the ingenuity of even the most experienced locksmith, while to manipulate such tools, if designed, would fall outside the skill of even the most clever operator.

The tam-penproof lock of the present invention offers numerous advantages over conventional axial tumblertype locks apart from the tamper-proof features of the invention. Whereas, in order to secure proper circumferential orientation of the key with the associated conventional or standard axial tumbler-type lock at the time of initial key entry, it is necessary to provide a spline connection between the key and the center post, any one of the radial slots that are associated with the lock of the present invention constitutes the female part of such a spline connection while the associated fin constitutes the cooperating male part of the spline connection. It is thus unnecessary to groove the center post as heretofore, or to spline the key. Still further, whereas, in order to prevent pulling of the key from the lock except in its initial entry position, or in some cases, additionally, in its fully turned locking position, it is necessary with a conventional axial tumbler-type lock to provide a radial retaining lug on the key which slides 'behind the front Wall of the protective cap or washer, the present lock requires no such retaining lug inasmuch as any one of the fins opcrates in the manner of such a lug to prevent key-removal except in an extreme position of the key. Thus, with the present lock, machining operations are reduced to a minimum and simplification of the lock and its associated key results.

The provision of a tamper-proof axial tumbler-type lock of the character briefly outlined above and possessing seer,

the stated advantages being the principal object of the invention, numerous other objects and advantages will readily suggest themselves as the nature of the invention is better understood.

In the accompanying two sheets of drawings forming a part of this specification, one illustrative embodiment of the invention has been shown.

In these drawings:

FIG. 1 is a perspective view of a key which is expressly designed for cooperation with the tamper-proof lock of the present invention;

FIG. 2 is a front perspective view of the lock;

FIG. 3 is a rear elevational view of the lock with parts broken away and other parts removed for illustrative purposes;

FIG. 4 is a front end elevational view of the lock;

FIG. 5 is a sectional view taken substantially along the line 5-5 of PEG. 4 with the key in position within the lock, certain parts being broken away in order more clearly to reveal the nature of the invention;

FIG. 6 is a sectional view similar to FIG. 5 but with a portion of the view being exploded and with other portions being brokenaway;

FIG. 7 is a perspective view showing the lock cylinder and the barrel assembly in separated relation;

FIG. 8 is a fragmentary perspective view illustrating the manner in which the key is arrested in its forward movement when initially inserted into the lock; and

FIG. 9 is a fragmentary perspective view similar to FIG. 8 but illustrating the manner in which ultimate effective key and tumbler registry is attained.

Referring now to the drawings in detail and in particular to FIGS. 1 and 2, a lock in accordance with the present invention is designated in its entirety by the reference numeral 16, and it comprises an outer lock cylinder 12, within which there is disposed a two-part barrel assembly 14- (see FIG. 7), such assembly consisting of a sleevelike rotatable part 16 and a sleeve-like fixed or nonrotatable part 18. The fixed part 18 is located in front of the rotatable part 16 and maintained within the cylinder 12 by means of a radial pin 20 (see FIG. 5). Such pin extends through a radial bore 22 in the cylinder 12 and into a socket 24 in the fixed part 18 of the barrel assembly 14.

Split pin-variety tumblers, each including a front driver pin 26 and a rear spring-pressed follower pin 27 (see FIGS. 3 to 8. inclusive) are arranged in an annular series about the axial of the cylinder 12 and are slidable longitudinally in respective bores 28 and 29 in the two barrel assembly parts 16 and 18. The tumblers are adapted to be displaced. by an annular series of radial fins 38 on a key 31 which is shown in detail in FIG. 1, and when they are so displaced that all of the joints or splits 32 between the adjacent ends of the rotatable driver pins 26 and the non-rotatable follower pins 27 are in register with the interfacial plane between the two barrel assembly parts 16 and 18, the rotatable part 16 may be turned within the lock cylinder 12 in the usual manner of key operation.

The lock cylinder 12 is provided at its front end with an enlarged head portion it having an inwardly extending front wall or flange 42. The latter constitutes a protective plate or flange and embodies a central circular opening 44 which is interrupted by the provision of an annular series of radial slots 46 in the flange 42. Adjacent solts 46 preferably, but not necessarily, are equally circumferentially spaced from each other so that the subtended angles are equal, six such slots being illustrated herein for exemplary purposes although a greater or a lesser number of slots may be employed if desired. The various radial slots 46 correspond in number and radial disposition to the number and disposition of the fins 3%) on the key 31. The radial extent of the various slots 46 also corresponds to the radial extent of the corresponding fins 30 on the key 31 so that the key may be introduced into the lock endwise through the central opening 4 only in one angular position. A lock shaft 50. projects completely through both the rotatable part 16 and the fixed or non-rotatable part 18 of the barrel assembly 14 and the extreme forward end region of this lock shaft constitutes a central pilot post 52 which cooperates with the key 31, in a manner that will be made clear presently, in order to align the key with the axis of the lock at the time of initial key entry. The lock shaft is pinned to the rotatable part 16 by means of a diametrically disposed taper pin 54 or the like (see FIG. 7) in order that such parts are conjointly rotatable.

As best seen in FIG. 1, the key 31 includes a cylindrical body portion 5'6 from which there projects axially a tubular shank 58. The latter presents a deep internal axial socket 6b which is designed for reception over the center post 52 in telescopic relationship when the key is initially introduced into the lock through the central opening 44 in the front flange d2 of the enlarged head porlions 4d. The previously mentioned radial fins 3d are formed exteriorly on the outer end region of the tubular shank 58 and the ends thereof that are adjacent to the outer or front end of the shank constitute shoulders for engaging the outer ends of the front driver pins 26 when the shank of the key is inserted into the circular opening a4 and then turned to a limited extent in order axially to align the fins 30 with the split tumblers. The key body 56 is provided with the usual manipulating wing 62.

he rear end region of the lock shaft 59 projects rearwardly beyond the rear rim. of the cylinder 12 and is provided with a reduced threaded extension 64-. The latter (see FIGS. 2, 3 and 6) has flattened sides 66 the inner portions of which result in the formation of a rearwardly facing stop shoulder against which there seats a washer-like stop disc '70. The latter is received over the extension 64 and is held against the stop shoulder by a nut 72 on the extension. Said stop disc 7 is formed with a pair of oppositely directed circumferentially spaced shoulders 74 and 76 (see FIG. 3) which cooperate with a stop lug 78 on the rear rim of the cylinder 12 to limit the extent of rotational or angular movement of the lock shaft 55% on the rotatable part 16 of the barrel assembly I4. A radially extending locking arm or plate 80 is disposed directly rearwards of the nut 72 and is secured on the shaft extension 64 by a second nut 82 (see FIGS. 3, 5 and 6). Said locking plate 89 is designed for cooperation with a fixed latch shoulder (not shown) on the jamb or otherpart of a cabinet door frame or other structure with which the present lock is associated. Both the stop disc 70 and the locking plate 80 are provided with openings (not shown) which are conformable to the cross sectional contour of the threaded shaft extension 64 to the end that they are constrained to turn with the lock shaft 50.

As shown in FIG. 6, helical compression springs 84 serve yieldingly to urge the tumblers forwardly. The front ends of these springs bear against the rear ends of the follower pins 27 and rear ends of the springs bear against the stop disc 70 when the lock parts are assembled as shown in FIG. 5.

Referring now to FIGS. 6 to 9, inclusive, it will be observed that the key 31 may enter the lock It) only in one angular position, i.e., when the various fins 36- on the tubular shank of the key become radially aligned with the corresponding slots 46 in the front flange 42 of the en larged head portion 40 of the cylinder 12. If desired, further to insure that the key shall not enter the lock in any but the correct angular position, not only may the radial extent of the fins and slots be varied, but also the width or thickness of these fins and slots may be varied, one of the fins 3tlA and its corresponding slot 46A being shown in FIG. 1 as being slightly wider than the width of the other fins and slots. When the key 31 is initially inserted into the lock iii as shown in FIG. 8, the various fins 30 will be out of axial register with the corresponding driver pins 26 in the bores 28. The driver pins 26 are formed with reduced forward extensions 90 (see FIG. 6) which project through restrictions 92 at the front of the bores 28, and thus, the pins 26 are captured within said bores against forward removal. Upon initial entry of the key 31 into the lock 10 as shown in FIG. 8, the key is blocked against full insertion thereof by reason of the provision of a forwardly facing land area or edge 100 at the bottom edge of a relatively wide notch 102 in the forward rim 104 of a forwardly extending sleeve-like extension 106 on the front end of the rotatable part 16 of the barrel assembly 14. This land area or edge 100 registers with and opposes the radial slot 46A and, consequently, at the time the key is initially inserted into the lock, the land area or edge 100 also opposes the radial fin A and limits the extent of entry of the key into the lock.

The relatively wide notch 102 is formed with a narrow rearwardly extending drop-off extension 108 in axial alignment, i.e., in the same radial plane with one of the driver pins 26, the slot extension being slightly wider than the width of the fin 30A on the key 31 and designed to receive the fin 30A therein when the initially inserted key is introduced into the lock and then turned in a clockwise direction under forward manual pressure so that the fin 30A will slide off of the land area or edge 100 and enter the slot extension 108. Such forward manual pressure serves not only to force the radial fin 30A into the notch extension 108, but also to depress the associated driver pin 26 at such time as the fin 30A moves into contact therewith. At the same time that the fin 30A engages the associated driver pin, all of the other fins 30 similarly engage their respective driver pins 26 and all of the pins together with their associated follower pins 27 are thus pushed rearwardly in the usual manner of axial tumbler operation to align the various tumbler splits with the interfacial plane of the fixed and movable parts 16 and 18 of the barrel assembly 14 and permit rotation of the key and the rotatable barrel assembly part 16 bodily in unison in a counterclockwise direction to effect a lock unlocking operation.

The straight linear edge 110 (see FIGS. 7, 8 and 9) which is common to the wide slot 102 and its drop-off extension 108 constitutes a reaction edge for engagement with the radial fin 30A when the key is turned in a clockwise direction to move the lock to its unlocked condition so that torque will be transmitted from the key to the rotatable barrel assembly part 16. Similarly, the shorter and opposite edge 112 of the slot extension 108 constitutes a reaction edge for the transmission of torque to the rotatable barrel assembly part 16 when the key is turned in a counterclockwise direction. The edge 114 of the notch 102 (see FIG. 9) which opposes the edge 110 constitutes a limit stop for the key 31 and the rotatable part 26 when the key arrives at its terminal position during counterclockwise turning thereof to bring the lock to its locked condition. This edge is effective as a limit stop inasmuch as when the fin 30A engages the edge 114, the tumbler bores 28 and 29 are aligned and the split pinvariety tumblers shift forwardly under the influence of the springs 84 to retain the rotatable part 16 against movefient with respect to the fixed part 18 of the barrel assem- The lock 10 is adapted to be installed upon a door D or other structure as illustrated in FIG. 6, the lock cylinder 12 passing through a hole or opening (not shown) in the door or other structure and the cylinder being held fixedly in position by a nut 122 which serves to clamp the rear annular end face 124 of the enlarged head hard against the forward side of the door.

From the above decsription, it is believed that the construction and operation of the herein described tamperproof lock 10 will readily be understood without further description. However, briefly to summarize the operation of the lock, the key 31, which may be introduced into the lock endwise in only one angular position, must be oriented so that the relatively thick and radially elongated fin 30A registers with the correspondingly wide and elongated slot 46A before the key may be pushed endwise through the central opening 44 and into the lock. Upon initial entry of the rear end of the key into the lock, the fin 30A immediately encounters the land area or edge (see FIG. 8) and further axial movement of the key rearwardly into the lock is prevented. The key may not be turned in a counterclockwise direction because of the existence of the side edge 114 of the wide notch 102, but may be turned in a clockwise direction. When so turned, the fin 30A moves to a position of longitudinal alignment with the drop-off extension 108 of the notch 102 and, thereafter, the key may be pushed rearwardly so that the fin 30A will enter the notch extension 108 and at the same time engage and force its associated driver pin 26 rearwardly. Simultaneously with such rearward movement of the key, all of the other fins 30 will engage their respective driver pins 26 and similarly force them rearwardly to bring the tumbler splits into the interfacial plane between the two barrel assembly parts 16 and 18, after which the key may then be further turned in a clockwise direction, together with the rotatable barrel assembly part 16. Such rotation of the barrel assembly part 16 transmits rotary motion to the lock shaft 50 and its threaded extension 64, thereby moving the lock parts to their unlocked condition. At no time after the key has been turned away from its initial position of entry into the lock may it be withdrawn from the lock due to the non-registry between the various fins 30 thereon and the radial slots 46. Only when these fins and slots have been restored to their original position of registry which obtained at the time of key-entry, may the key be removed. In such a position, of course, the lock will have been restored to its locked condition by a reversal of the aforementioned locking procedure.

By reason of the fact that the various driver pins 26 are offset in a circumferential direction with respect to the radial slots 46 in the front flange or wall 42 of the head 40, these pins are concealed behind solid or imperforate portions of the flange or Wall and, therefore, they are inaccessible for manipulation except by the use of a proper key such as the key 31. The tortuous passage leading from any one of the radial slots 46 to the adjacent forward end of any one of the driver pins 26 is such that it would be impractical to design a lock-picking tool that is shaped to reach the pin through the slot. Furthermore, a lock-picking tool so designed could not be introduced through the slot so that it would reach the desired pin. Finally, for a person to design and construct a number of such lock-picking tools and manipulate them all simultaneously would be a feat which lies beyond human skill.

The invention is not to be limited to the exact arrangement of parts shown in the accompanying drawings or described in this specification as various changes in the details of construction may be resorted to without departing from the spirit or scope of the invention. For example, in its broadest aspect, the invention contemplates the provision of a protective plate which is suitably positioned in front of the cylinder and is provided with an opening therein for reception of the shank portion of the key, the contour of the opening being such that the shoulders on the key may not be brought into operative register with the tumblers of the lock until after the shank portion has been passed through the openings to a predetermined degree and then shifted bodily to a predetermined position. Therefore, only insofar as the invention has particularly been pointed out in the accompanying claims is the same to be limited.

Having thus described the invention what I claim as new and desire to secure by Letters Patent is:

1. In an axial tumbler-type lock of the character described, in combination, a lock cylinder having an axial bore extending therethrough and provided with a front rim having an inwardly extending flange defining a central circular opening designed for axial reception therethrough of the operating end of a cylindrical key shank, an annular sleeve-like front rotatable part and an annular sleeve-like fixed part disposed within said bore and presenting relatively slidable faces which meet on an interfacial plane, a lock shaft projecting through said parts and secured to the rotatable part for rotation in unison therewith, longitudinal bores in said fixed and rotatable parts respectively movable into and out of alignment, split-pin tumblers in said bores and including driver pins slidable in j the bores of the rotatable part and projecting forwardly thereof, there being a series of radial slots in said inwardly extending flange communicating with the central opening, adjacent slots defining therebetween imperforate portions, the forward ends of said driver pins being out of axial register with said radial slots and being disposed directly behind said imperforate portions whereby they are concealed within the lock cylinder, and a key having a cylindrical shank receivable through said central opening and provided with a series of tumbler-engaging radially extending fins thereon corresponding in number and radial disposition to the number and radial disposition of the radial slots in said flange whereby registry between said fins and slots may be effected to permit insertion of the shank into said central opening, the bores in said rotatable part being circumferentially arranged with a spacing corresponding to the radial disposition of the fins and slots, the forwardly projecting portions of said driver pins being spaced rearwardly from said flange a distance greater than the axial extent of said fins to the end that after insertion of the shank of the key into said central opening the key may be rotated to bring the fins into longitudinal register with said driver pins.

2. An axial tumbler-type lock as set forth in claim 1 and wherein the lock shaft is provided with a forwardly extending pilot post thereon in axial register with said central opening and the shank on the key is formed with a socket telescopically receivable over said pilot post.

3. An axial tumbler-type lock as set forth in claim 1 and wherein said radial fins and slots lie in equi-angularly disposed radial planes and one radial fin and its corresponding radial slot are of greater radial extent than that of the remaining radial fins and slots.

4. An axial tumbler-type lock as set forth in claim l and wherein said radial fins and slots lie in equi-angularly disposed radial planes and one radial fin and its corresponding radial slot are of greater thickness and width respectively than the thicknesses and widths of the remainmg radial fins and slots.

5. An axial tumbler-type lock as set forth in claim 1 and wherein said radial fins and slots lie in equi-angularly disposed radial planes, one radial fin and its corresponding radial slot are of greater radial extent than that of the remaining radial fins and slots, and said one radial fin and its corresponding radial slot are of greater thickness and width respectively than the thicknesses and widths of the remaining radial fins and slots.

6. In an axial tumbler lock of the character described, in combination, a lock cylinder having an axial bore extending therethrough and provided with a front rim having an inwardly extending flange defining a central circular opening designed for axial reception therethrough of the operating end of a cylindrical key shank, a rotatable barrel disposed Within said cylinder and having a front end face disposed rearwardly from said flange, a series of circumferentially arranged depressible driver pins projecting forwardly from said end face and disposed in equi-angularly disposed radial planes, a cylindrical sleevelike extension on the forward end of said barrel and encompassing said driver pins, said flange being formed with a series of radial slots therein communicating with said central opening, adjacent slots defining therebetween imperforate portions, said driver pins normally being 8 disposed out of axial register with said radial slots and being disposed directly behind said imperforate portions wherein they are concealed within said cylindrical extension, and a key having a cylindrical shank receivable through said central opening and provided with a. series of driver pin-engaging radially extending fins thereon corresponding in number and radial disposition to the numher and radial disposition of said radial slots whereby registry between said fins and slots may be effected to permit insertion of the shank into said central opening, said driver pins normally being spaced rearwardly from said flange a distance greater than the axial extent of said fins to the end that after insertion of the shank into said central opening the key may be rotated to bring the fins into longitudinal register with said driver pins, one of said fins and its corresponding slot being of greater radial extent than the radial extent of the remaining fins and their corresponding slots and being of such radial extent that it is engageable with the forward rimof said cylindrical extension when the key is inserted into said central opening, said fonward rim of the cylindrical extension being provided with a notch therein in longitudinal register with said one slot and the bottom of which notch is engageable with said one fin to limit the extent of forward movement of the key during initial insertion thereof through said central opening, the bottom of said notch being formed with a drop-off extension for said one fin, said drop-off extension being in longitudinal register with one of said driver pins,

7. In an axial tumbler look, a lock cylinder, a lock barrel rotatable within said cylinder between locking and unlocking positions, a series of circurnferentially spaced cylindrical tumbler pins slidable axially in said barrel and projecting fonwardly therefrom, a key having a shank providing a series of pin-engaging shoulders designed for engagement with the forward ends of said tumbler pins and for subsequent depression of the pins when the shank is axially aligned with the lock cylinder, a fixed protective plate connected to the front end of the lock cylinder, positioned forwardly of and axially spaced from said tumbler pins, and having fixed portions thereof completely intersecting and covering the extended cylindrical confines of said tumbler pins and thereby fully concealing the same, there being an opening in said plate through which said shank is adapted to be projected when the key is initially applied to the lock, and cooperating means on the plate and the key effective positively to prevent axial alignment of the shoulders with the tumbler pins during initial insertion of the shank through said opening and effective after such initial insertion to permit movement of the shank to bring such shoulders into axial register with the pins for subsequent depression of the pins by the shoulders.

8. In'an axial tumbler lock, a lock cylinder, a lock barrel rotatable Within said cylinder between locking and unlocking positions, a series of circumferentially spaced driver tumbler pins slidable axially in said barrel and projecting fonwardly therefrom, a key receivable axially in said cylinder and having pin-engaging portions thereon designed for engagement with the forward ends of said tumbler pins, means on said lock cylinder andengageable with said pin-engaging portions for preventing rotation of the key and for maintaining said portions, out of axial register with said tumbler pins during initial projection of the key axially into the lock cylinder, said means being ineffective after the key has been projected into the lock cylinder a predetermined extent whereby the key may then be rotated to bring said portions into axial register with said tumbler pins.

9. In an axial tumbler lock, in combination, a lock cylinder having an inwardly extending front Wall provided with a central key-receiving opening and with a series of radial slots communicating with said opening, adjacent slots defining therebetween imperforate wall sectors, a barrel member disposed within said cylinder and rotatable between locking and unlocking positions, a series of driver tumbler pins slidable axially in said barrel member, projecting forwardly thereof and spaced rearwardly from said Wall, said pins being out of axial register with said slots When the barrel member is in its locked position, and a key receivable through said opening and provided with a series of radially extending, pin-engaging fins thereon corresponding in number and disposition to the number and disposition of said radial slots.

References Cited by the Examiner UNITED STATES PATENTS 1,619,252 3/1927 George 70-3 63 3,102,412 9/ 1963 Christopher 70-363 EDWARD C. ALLEN, Primary Examiner.

P. TEITELBAUM, Assistant Examiner.

George 70-3 63 X 

8. IN AN AXIAL TUMBLER LOCK, A LOCK CYLINDER, A LOCK BARREL ROTATABLE WITHIN SAID CYLINDER BETWEEN LOCKING AND UNLOCKING POSITIONS, A SERIES OF CIRCUMFERENTIALLY SPACED DRIVER TUMBLER PINS SLIDABLE AXIALLY IN SAID BARREL AND PROJECTING FORWARDLY THEREFROM, A KEY RECEIVABLE AXIALLY IN SAID CYLINDER AND HAVING PIN-ENGAGING PORTIONS THEREON DESIGNED FOR ENGAGEMENT WITH THE FORWARD ENDS OF SAID TUMBLER PINS, MEANS ON SAID LOCK CYLINDER AND ENGAGEABLE WITH SAID PIN-ENGAGING PORTIONS FOR PREVENTING ROTATION OF THE KEY AND FOR MAINTAINING SAID PORTIONS OUT OF AXIAL REGISTER WITH SAID TUMBLER PINS DURING INITIAL PROJECTION OF THE KEY AXIALLY INTO THE LOCK CYLINDER, SAID MEANS BEING INEFFECTIVE AFTER THE KEY HAS BEEN PROJECTED INTO THE LOCK CYLINDER A PREDETERMINED EXTEND WHEREBY THE KEY MAN THEN BE ROTATED TO BRING SAID PORTIONS INTO AXIAL REGISTER WITH SAID TUMBLER PINS. 